SGM3124 White LED Charge Pump Current Source with PWM Brightness Control

GENERAL DESCRIPTION

The SGM3124 is a charge pump with PWM brightness control for white LED supplies in LCD display backlight applications. The supply voltage ranges from 2.7V to 5.5V, it is ideally suited for all applications powered by a single Li-ion battery cell or three to four NiCd, NiMH, or alkaline battery cells.

The device provides a constant current for each LED, and the initial current value can be set by an external resistor. High efficiency is achieved by utilizing a 1×/1.5× fractional conversion technique in combination with very low dropout current sources.

The SGM3124 is capable of driving up to three channels of LEDs at 30mA per channel from a 2.7V to 5.5V input. Additionally, the current controlled charge pump ensures low input current ripple and EMI. A low external part count (two 0.47μF flying capacitors and two small 1μF capacitors at VIN and VOUT) makes this part ideally suited for small, battery-powered applications.

The SGM3124 is available in a Green, space-saving TQFN-3×3-16L package, and is rated over the -40℃to +85℃ temperature range.